The present invention relates to a cleaning device for cleaning a fabric, such as wire or felt used in paper machines, paperboard machines or similar, according to the preamble of the first claim presented below.
In paper machines, paperboard machines or similar the fabrics used to support the web, such as the wires of the wet end and the dry end and the felts of the press section, will absorb fiber material and impurities which gradually block the fabric and prevent the water from migrating through the fabric, if the fabric is not cleaned from time to time. Therefore cleaning devices are used for instance in the wire return loop in order to clean the wire as it passes over the wire guide roll or similar.
A typical cleaning device comprises a water nozzle having a water jet, with which the fabric is cleaned as the fabric passes over a roll supporting the fabric. The cleaning device is movably fastened to a supporting beam or similar extending over the web, whereby the cleaning device can be moved back and forth across the fabric, and the fabric can be cleaned over the whole width of the fabric. The water supply conduits for the nozzle can be arranged within the supporting beam.
It is difficult to access the knots of the fabric with a water jet which has a perpendicular direction toward the fabric. Therefore it has been proposed to rotate the nozzle, whereby the water can better penetrate the knots and remove the fibres and impurities located there.
The publication WO 97/42373 proposes to mount a motor in the cleaning device in order to rotate the nozzle. The publication U.S. Pat. No. 5,783,044 proposes a cleaning device comprising one or more rotating nozzle heads. The nozzle heads are rotated by spraying water from them in a tangential direction. Rotating nozzles provide a good cleaning result.
However, some disadvantages are connected with the use of a rotating nozzle. The effectuation of the rotational motion e.g. with the aid of a motor increases the weight of the cleaning device, its space requirements and its price. Further, a rotating nozzle requires a rotating connector for the water supply, which forms a separate maintenace object.
Therefore the object of the present invention is to provide a new improved cleaning device.
The object is particularly to provide a cleaning device where the movement of the water jet from the nozzle is obtained with simple means.
Then an object is also to provide a cleaning device which avoids the use of moving joints and motors.
In order to attain the above mentioned objects the cleaning device according to the invention is characterised in what is defined in the characterising clause of claim 1 presented below.
A typical cleaning device according to the invention comprises
first tilting means which turn the nozzle back and forth around a first turning point in a first plane in the direction of the water jet from the nozzle, so that the water jet obtains a first linear motion. Further, the cleaning device preferably comprises second tilting means which turn the nozzle back and forth around a turning point in a second plane in the direction of the water jet from the nozzle, so that the water jet in addition obtains a second linear motion.
The nozzle of the cleaning device and the tilting means are preferably mounted in a mounting plate which is easy to fit in a desired place of the paper machine. Then the nozzle is preferably fastened so that it is journalled in an opening made in the mounting plate, for instance by a spherical surface valve, and so that the fastening forms a turning point for the nozzle mainly at the bearing, around which turning point the nozzle can freely turn as the tilting means turn the nozzle.
The first tilting means are advantageously arranged to turn the nozzle back and forth around a turning point so that the water jet discharged from the nozzle obtains a linear motion in the travelling direction of the fabric. Correspondingly, the second tilting means are advantageously arranged to turn the nozzle back and forth so that the water jet discharged from the nozzle obtains a linear motion which is perpendicular regarding the travelling direction of the fabric. When desired, it is, of course, possible to direct the water jets with the tilting means so that they obtain a motion in a direction which is different from the above mentioned directions.
Advantageously the cleaning device is arranged at such a distance from the fabric, and the nozzle is advantageously continuously tilted back and forth so, that the water jet discharged from the nozzle covers an area having a length of about 5 cm in the travelling direction of the fabric and a width of about 5 cm in the cross-direction of the fabric. Typically the nozzle is turned about 15xc2x0.
The first and/or the second tilting means are preferably cylinders, such as pneumatic cylinders, with which the upper part of the nozzle can be alternately pushed away from the cylinder and alternately pulled closer to the cylinder.
Advantageously the cleaning device can be fastened to a supporting beam arranged transversely above the fabric, along which beam the cleaning device can be moved in the cross-direction of the fabric. The apparatus related to the supply of water, compressed air and electricity can be mounted in the beam.
It is advantageous to locate in the cleaning device a collecting hood or similar for the used cleaning water, from which hood the water can be directed away from the system along water channels.
With a cleaning device according to the invention the water can be easily spread over a large area and the cleaning water jets can hit the fabric""s surface at different angles, whereby the fabric and also its knots are well cleaned. With a device according to the invention the cleaning water jets can be directed toward the fabric""s surface at different angles without rotating the nozzle and without any motor. Also, the cleaning device does not require moving joints for the water supply, as the water can be directed to the nozzle via a flexible water hose.